1. Field of the Invention
The present invention relates to a navigation system and particularly relates to a navigation system capable of instantly transmitting real-time information to a navigator mounted on a client""s vehicle.
2. Description of the Background Art
A conventional navigation system is constituted to measure the position and azimuth of a client""s vehicle by GPS (Global Positioning System), a speed sensor, an azimuth sensor and the like, and to display the measured positional information at need while superposing the information on map information read from a CR-ROM or an IC memory.
Further, Japanese Patent Laying-Open No. 10-224291(1998) describes a mobile object communication equipment wherein if a client transmits a request to describe a present position on map information from the on-vehicle equipment of a client""s vehicle to the closest server among a plurality of servers through a telephone network, the server transmits data such as road traffic information around the client, nearby parking lots, vacancy information on the parking lots, shop information, advertisement and tourist guides as well as map information describing the present position of the client, to the on-vehicle equipment of the client.
However, the conventional navigation system only displays map information describing a present position and not display the traffic state of the road on which the client""s vehicle is traveling. Due to this, the client cannot instantly make the next judgment. That is, the conventional navigation system has a disadvantage in that the client cannot instantly judge whether to travel on a road on which the client is currently traveling or to change the road to another road.
Meanwhile, according to the mobile object communication equipment disclosed by Japanese Patent Laying-Open No. 10-224291(1998), traffic information on roads around the client is transmitted to the client. However, since the road traffic information is information on areas near the client, the client cannot accurately judge whether or not to change the present road.
It is, therefore, an object of the present invention to provide a navigation system for transmitting real-time information allowing a client to instantly judge the next action while moving by a vehicle.
A navigation system according to the present invention includes: a database holding real-time information indicating a ground state; a server receiving positional information including a present position of a client through a satellite communication network, determining, as an information extraction range, a certain range on a map wider than a surrounding area of the present position based on the positional information, extracting, as real-time information to be transmitted, real-time information falling within the information extraction range and having a transmittable largest data quantity from the database, adding a header identifiable by the client to the extracted real-time information and transmitting the header-added real-time information through the satellite communication network at random; and a navigator transmitting the positional information to the server through the satellite communication network, receiving information from the server through the satellite communication network, detecting the extracted real-time information from the received information while using the header, and displaying the detected real-time information.
In the navigation system according to the present invention, if the navigator transmits positional information such as the client""s present position to the server, the server transmits real-time information on areas in the traveling direction of the client to the client""s navigator. Then, the navigator displays the received real-time information. According to the present invention, therefore, the client can instantly make various judgments based on the received real-time information.
Preferably, the server of the navigation system determines a certain range on an orthogonal coordinate with the present position set as an origin, as the information extraction range.
If receiving the client""s present position from the navigator, the server transmits real-time information which falls within a certain range with the present position set as an origin, to the navigator. According to the present invention, therefore, information on not only the road on which the client is traveling but also on traffic states of other roads and shops can be transmitted to the client.
Preferably, the server of the navigation system updates the real-time information held by the database at certain time intervals or every time the positional information from the client is received.
The real-time information held in the database is updated at random. According to the present invention, therefore, it is possible to transmit update real-time information to the client.
Preferably, the navigator of the navigation system extracts real-time information falling within a designated range inputted by the client from the received real-time information based on the designated range inputted by the client, and displays the extracted real-time information.
In the navigator, the received real-time information is further limited and extracted based on the designation range inputted by the client. According to the present invention, therefore, the client can select only the necessary real-time information from the real-time information received from the server and use the selected real-time information.
Preferably, the real-time information is a traffic state from the present position to a destination.
The navigator displays the traffic state from the present position to the destination received from the server on the display unit, and the client determines a road on which the client is to travel while looking at the displayed traffic state. According to the present invention, therefore, the client can arrive at the destination while avoiding the congestion of the roads.
Preferably, the navigator of the navigation system transmits moving time of the client from the present position to the server through the satellite communication network; and the server detects a range in which the client can move within the moving time based on traffic states of roads around the present position, and determines the detected range as the information extraction range.
A range in which the client can move within the certain time is determined as a range for extracting real-time information based on the congested state of the surroundings of the client""s present position. According to the present invention, therefore, it is possible to know a place to which the client can move within the certain time.
Preferably, the real-time information includes a congested state of a restaurant; the navigator transmits a request inputted by the client to make a reservation at the restaurant to the server through the satellite communication network; and the server receives the reservation request through the satellite communication network, executes the requested reservation, and transmits an execution result to the navigator through the satellite communication network.
If the client transmits a request to make a reservation at a restaurant while looking at the congested state of the restaurant transmitted from the server, the server executes the restaurant reservation and transmits the result to the client. According to the present invention, therefore, the client can easily make a restaurant reservation even while moving by vehicle. As a result, wait time after the client arrives at the restaurant can be shortened.
Preferably, the real-time information includes a congested state of a shop, an article display state and a traffic state near the shop.
The client determines whether or not to do the shopping at a shop while looking at the congested state of the shop, the article display state of the shop and a traffic state near the shop displayed on the display screen of the client""s navigator. If the client decides to do the shopping at the shop, the client selects an article which the client wants to buy from among the articles displayed on the screen. According to the present invention, therefore, it is possible to efficiently do the shopping without the need to select an article after arriving at the shop.
Further, a navigation system according to the present invention includes: a database holding real-time information indicating a ground state; a server receiving positional information including a present position of a client through a satellite communication network, determining, as an information extraction range, a certain region on a map wider than a surrounding area of the present position based on the positional information, extracting, as information to be transmitted, real-time information falling within the information extraction range from the database, adding a header identifiable by the client to the extracted real-time information, and transmitting the header-added real-time information through the satellite communication network at random; and a navigator transmitting the positional information to the server through the satellite communication network, receiving information from the server through the satellite communication network, detecting the extracted real-time information from the received information while using the header, and displaying the detected real-time information, wherein the server receives surrounding information on the client from a plurality of clients, and updates the real-time information in the database using the received surrounding information.
In the navigation system according to the present invention, the server updates the real-time information held in the database using the surrounding information on a plurality of clients. According to the present invention, therefore, it is possible to provide carefully thought out services to the respective clients.
Preferably, the surrounding information is information on an electrical system of a vehicle taken by the client.
The navigator mounted on the vehicle transmits information on the electrical system such as the turning on and off of the wiper of the vehicle or the turning on and off of the switch of an ABS to the server, and the server can detect the surrounding state of the client based on the information on the electrical system of the vehicle. According to the present invention, therefore, it is possible to obtain a lot of surrounding information from respective clients.
Preferably, the surrounding information is a history of the vehicle taken by the client. According to the present invention, therefore, it is possible to provide information so as to prevent a vehicle which has transmitted a history from having an accident.
Preferably, the surrounding information is a wiper speed of the vehicle taken by said client. According to the present invention, therefore, it is possible to provide weather information in the place where the client takes the vehicle.
Preferably, the server receives the surrounding information from the plurality of clients at certain time intervals.
The server updates the real-time information held in the database using the surrounding information on the client at predetermined time intervals. According to the present invention, therefore, the database can always hold update real-time information.
Preferably, the server extracts the real-time information falling within the information extraction range from the real-time information updated using the surrounding information, and transmits the extracted real-time information to the navigator through the satellite communication network.
The real-time information obtained from a plurality of clients is transmitted to the other clients in accordance with requests from the other clients. According to the present invention, therefore, it is possible to transmit real-time information useful to more clients.